Advise needed please ,just starting out in the world of Trials with a  Fantic 303 ...

Confused about oils ...mineral or Synthetic ?  Mix ratios?

Any suggestions would be gratrfully recieved

Manuals for air cooled bikes usually recommended 32:1 but that was in large part due to the variability in oil and fuel quality and a margin of safety built into the recommendation. If you have access to a good quality synthetic oil 50:1 will work fine. I ran Bel-Ray MC-1 for decades at 50:1 in everything from Maicos to Bultacos to Can-Ams (Armstrong) with never an oil related failure. Now having said that I assume you are riding the mighty Fantic like a trials bike and not flogging it like it was a short legged MX bike. I've seen that done and it causes "unusual" wear in a trials engine.

The recommended ratio by Fantic back in the day on a then ordinary oil was 50 to 1 (don't know about the 303 but earlier models had the measure in the filler cap).  No need for full synthetic really as any oil nowadays should be superior to that of 35 years ago.

I was thinking stick with mineral oil.... is castrol 2t a good one or is there a more superior mineral based to use?.

On 20/6/2017 at 8:44 AM, pwadz said:

I was thinking stick with mineral oil.... is castrol 2t a good one or is there a more superior mineral based to use?.

40 years ago Fantic recommended run with mineral oil at 2% (50:1)

now i race the 240 and 300 at 1.2% (80:1)  with synt oil (Motul 800-710 or other brand )  without any unusual wear, i tell you this because i have demounted my engine last year and the interior of the engine was perfect, so i think it's not necessary run at high percentage

 

I think for most bikes, 50-1 is the sweet spot, with modern oils  

Edited June 22, 20179 yr by shakennstirred

On 21/6/2017 at 8:28 PM, oni nou said:

Its a great STORY but running at 80:1 in an aircooled engine in Italy where it is probably warmer than it is in the UK......just not possible...... your  engines are definitely ruined,I should have another look and rebuild them then use a bucket full of oil to a cup full of petrol.

i have some trouble to translate (sorry) but i understand that you think it's not possible to run at 80:1  ?

i ride my Fantic trial from years only in classic competition and trial practice, usually 10 liters gasoline 100 octane with 140 cc of sinthetic oil but last year i cheked ours engine and discovered inside a lot of deposit on pistons and head, and watching the bearing, pistons and cylinders they were full covered of oil (like a four stroke) so i decided (after suggest of my mechanic) to reduce the oil at 80:1 (our Beta evo run at 90:1)

consider that ossa and vertigo run at 120:1 and they run well, Beta enduro 250/300 2t self mix run from 0.8% to 1.6%

this is what really happen here in Italy in my garage and see with my eyes, and yes here is very hot  ... but i never ride my bike on street and at high rpm

here some picture of the last race

https://photos.google.com/share/AF1QipNlZCrobxsjOg8fwmSWbOouAbywQqfEo4QGUyZjfgGwZ8DitkbchgjDz308qxYFuA?key=WTBTYU9OVG1mU3VaVjlkemNJUWlzSWhtOHN2Qldn

I run all of my 1980 Fantics (200's, 125, 201, 241 and 301) at 70:1 with fully synthetic (Castrol XR77) and have done for years with no issues at all. 50:1 is way to much oil if you're using synthetic and I shudder to think how bunged up your pipe (!) would get with 32:1!!!

Not an aircooled Mono, but I run my TYZ at 80:1 on Putoline MX5

On 14/07/2017 at 6:21 PM, oni nou said:

You need to talk to dadof2 he says that even at 25:1 your exhaust will stay whistle clean with quality oil and fuel plus correct jetting and set up..................?

You may have seen a post on here about UK Vertigo bikes running at 200:1 this advice coming from the UK importer and obviously with the knowledge of the Factory.

Hmm, we'll agree to differ I think. 70:1 is right for me and my bikes and I'm sticking to that.

I've been running all my Fantics (air & water cooled) @ 75:1 with amsoil synthetic with not a issue ever with fuel ... oh , mixed with 110 ave fuel ....